For a long time it was odd to me that cacti have lots of spikes and big thorns. I supposed that the goal was to ward off big ruminants like cows, but that doesn’t really make much sense, since the desert isn’t really overflowing with big animals that eat a lot of plants.
It turns out that protection from predators is only a secondary goal. The main goal is protection from the environment. The spikes capture and slow the air moving around the plant, to preserve moisture and protect against the heat.
Wavelengths of visible light are around ~500 nm. Even infrared is on the order of micrometers. I don’t think the spikes that we’re imagining are micrometers apart.
Looks like photon density is a thing. I was under the impression that I read somewhere that spikes can intercept (harsh desert) light and make it less harmful to the plant
For a long time it was odd to me that cacti have lots of spikes and big thorns. I supposed that the goal was to ward off big ruminants like cows, but that doesn’t really make much sense, since the desert isn’t really overflowing with big animals that eat a lot of plants.
It turns out that protection from predators is only a secondary goal. The main goal is protection from the environment. The spikes capture and slow the air moving around the plant, to preserve moisture and protect against the heat.
Hang on, I’m not sure I buy it. Why are they so thin, hard and sharp then? Some kind of fuzz or flat leaves would work better.
There are lots of cacti that are mostly hairy/fuzzy instead of pointy.
In terms of air flow protection purchased vs biological effort expended, I’m not sure a leaf is better than a spike.
The fur/spike can also be at specific widths to block certain wavelengths of light
Wavelengths of visible light are around ~500 nm. Even infrared is on the order of micrometers. I don’t think the spikes that we’re imagining are micrometers apart.
https://www.ncbi.nlm.nih.gov/pubmed/18507791
Looks like photon density is a thing. I was under the impression that I read somewhere that spikes can intercept (harsh desert) light and make it less harmful to the plant
No, they can be micrometers wide and long enough to cause disruption of waves